如何查看表、索引、表空间、数据库大小？

select indexrelname,pg_size_pretty( pg_relation_size(relid))   
from pg_stat_user_indexes 
where schemaname =  'schemaname' order by pg_relation_size(relid) desc;

select relname, pg_size_pretty(pg_relation_size(relid))  
from pg_stat_user_tables 
where schemaname =  'schemaname' order by pg_relation_size(relid) desc;

select pg_database.datname,pg_size_pretty(pg_database_size(pg_database.datname)) AS size  
from pg_database;

select pg_tablespace_size('tbs_index')/1024/1024  as  "SIZE M";